Custom Javascript for Form on Instapage Landing Pages

Looking for an experienced Javascript Programmer to write a script that associates Marketo's 'Munchkin' Cookie with Email Address field on Instapage form when a user submits it. I believe this can also be done via REST / SOAP API so having some PHP knowledge would be helpful. If you are new to Marketo & Instapage, Marketo is an email automation tool just like Mailchimp, but more advance. Instapage is a simple landing page builder tool. What is Munchkin? It's basically a cookie that is stored on a user's browser by Marketo when they visit one of our Instapage landing pages (eg: [login to view URL]). This cookie stores all the page visit activity of the user anonymously, but we can identify this activity and link it with a user's profile on Marketo if they fill up a form. (Considering cookie is not cleared from browser) What is required? We require a script written in Javascript or PHP that links the Munchkin cookie with user's form submission on Instapage. It will basically have the cookie ID and email address of the user. You can read more details here - [login to view URL] (Scroll down to section that says 'associateLead') Happy to answer any questions and discuss further.